your best chance is either your dissertation supervisor or your academic advisor. Just send them an email saying you would appreciate it if they offered to be your reference, and give them as much info about you and your time at university. They probs wont know much about you, so you giving the info for them will be really helpful. And maybe also attach your CV to give them more info too. Dont feel awkward to having to ask for the reference; it's literally their job and they know how important it is. Just remind them who you are and they'll defo be willing to help
some employers will also be willing to take references from a "good standing person in their community" if you don't have a work reference.